In prior art, most analog door entry systems are single-channel systems, each of which uses a Cat.5 or Cat.5e cable with 4 twisted pairs for transmitting the power supply, audio, video and data signals respectively. Therefore, the intercom function of door entry systems is realized based on the single channel.
There are more and more high-rise residential buildings and communities appearing with multiple entrances in cities. When a single-channel analog door entry system is implemented for such buildings or communities, due to a large quantity of users, the users will frequently encounter the “line is occupied” or “line is busy” issues and wait until the line is available or released, otherwise try it next time. The issue of “line is busy” is caused by the simultaneous intercoms among other users at that moment, for example, between another outdoor station and an indoor phone. It's obvious to degrade the efficiency of the intercom system and customers' satisfaction.
Due to the above mentioned problems, the present invention is to propose a dual-channel analog door entry system and a method thereof.